The vast majority of American adults eat a dietary pattern that falls short of meeting national dietary guidelines for cancer prevention, according to a study, ‘US Adults Fall Short of the Dietary Guidelines for Cancer Prevention Regardless of BMI Category’, was published in the Journal of the Academy of Nutrition and Dietetics.
When researchers analysed the dietary intake of more than 30,000 American adults according to body mass index (BMI), the results also showed that people with BMI>30 were the least likely to adhere to the dietary recommendations intended to reduce the risk for cancer.
The analysis measured self-reported dietary recalls and diet quality. Though the percentages of American adults who met each food source category differed, between almost 63% and 73% fell short of the recommended daily intake of fruits and vegetables and whole grains, and roughly 90% failed to meet the 30 grams of fibre per day recommendation.
The cancer-prevention guidelines updated by the American Institute for Cancer Research (AICR) in 2018 and the American Cancer Society nutrition and physical activity guideline closely mirror the 2020-2025 Dietary Guidelines for Americans recommended by the US Department of Agriculture - suggesting that most US adults are eating a suboptimal dietary pattern when it comes to nutrition-related disease prevention.
"We're looking at individuals to move toward a primarily plant-based type of dietary pattern rich in fruits and vegetables, whole grains and beans, peas, lentils, seeds and nuts – and cutting back on saturated fats and sodium," said senior study author, Dr Colleen Spees, associate professor of medical dietetics in the School of Health and Rehabilitation Sciences at The Ohio State University. "Modifying our current dietary and physical activity patterns to better align with these evidence-based guidelines over time is important to reduce the risk of noncommunicable disease and promote lifelong health and wellness. If Americans adopt these recommendations, they can reduce their risk of obesity, cancer, cardiovascular disease, stroke and high blood pressure."
The research team used data from the National Health and Nutrition Examination Survey (NHANES), which collects health information on a nationally representative sample of about 5,000 individuals in the US every year through interviews, laboratory tests and physical exams.
The sample for this study included 30,888 adults aged 18 and older. The Ohio State researchers analysed data from 24-hour dietary recalls participants completed as part of the NHANES survey as well as their BMI.
Almost 70% of the sample were classified as overweight or obese, and adults in the obesity range (35.9% of all participants) were significantly less likely than other adults to meet recommended intakes of fibre, fruit, non-starchy vegetables and whole grains. Adults with obesity were also more likely to exceed the recommended 18 ounces per week of red meat and to have consumed fast food on the day of survey participation.
All groups, on average, consumed more added sugars than the recommended maximum of less than 10% of overall daily calories.
While basing the analysis on what survey participants reported eating over the previous 24 hours is a limitation of the study, Spees noted that previous studies have shown that 24-hour recalls can provide a representative snapshot of American dietary patterns.
Spees added these results may also reflect common “reductionist" views of dietary patterns among Americans - namely, the fixation on fad diets that often exclude certain food groups that the public is led to believe can cancel out a lifetime of marginal eating patterns.
"Is coconut oil good for me? Is a single egg good for me, or not?" she said. "That's a reductionist view and perspective when what really shapes and defines our health outcomes throughout life are dietary patterns – the cumulative patterns over time, and over years – as well as our patterns of behaviours, including our physical activity, our sleep patterns, our stress levels.
"It almost appears as if many Americans believe that if they can't follow all of the recommendations, why should they adhere to any of them? And that's just not the case. These guidelines don't have to be so prescriptive. Even little changes in behaviour can have a huge impact. For instance, reducing added sugars can help individuals achieve and maintain a healthy weight status over time."
The USDA and cancer-prevention agencies are the most reliable sources for not just what the guidelines are, but how to incorporate them into daily life, said Spees, also an investigator in Ohio State's Comprehensive Cancer Center.
Meeting some of the guidelines is far better than disregarding expert advice altogether, she said: Eat out at fast food restaurants a little less often and find tasty ways to incorporate more vegetables, grains and beans into meals prepared at home. If you can't exercise the suggested 150 minutes per week, then simply sit less and move more. And as you make such changes, do it gradually, in a way that is sustainable – and ideally, for the rest of your life.
While this study found that people whose BMIs classify them as obese were the least likely to adhere to the guidelines, Spees said there is a bigger problem to consider: "Most Americans, regardless of weight status, have much to improve when it comes to dietary patterns."
Co-authors include Madisyn Good, Ashlea Braun and Christopher Taylor, all from Ohio State.